Optimal powering of light sources such as LEDs for time-of-flight (TOF) devices requires specialized regulators that minimize intensity variations, e.g. with battery voltage and uniform pulse output. For this purpose, there are two regulators types often used: inductor-based boost converters and capacitor-based charge-pump converters. Each regulator type has specific advantages/disadvantages.
Application note 3243 (http://www.maxim-ic.com/an3243) of Maxim Integrated Products describes a comparison between LED Boost Converters and Charge Pump circuits. This article compares state-of-the-art regulators, namely the MAX1561 boost converter versus the MAX1573 charge pump. FIG. 7 shows the boost converter and the charge pump of FIG. 1 of this document. The article suggests advantages for the charge pump.
A time of flight camera usually comprises an illumination device configured for illuminating an object, and a detection device configured for detecting light received from the illuminated object. The time of flight camera is configured for determining a phase difference between the light emitted by the illumination device and light reflected by the object and received by the detection device, in order to reconstruct an image of the illuminated object.
US 2011/0018451 A1 describes an light emitting diode (LED) driver circuit configured for driving a plurality of LED strings which are arranged in parallel to one another and each of the LED strings comprising a plurality of LEDs connected in series to one another. The LED driver circuit comprises a voltage regulation loop and a current regulation loop for controlling an amount of light emitted by the plurality of LEDs. The voltage regulation loop and the current regulation loop are configured for controlling an amount of voltage inputted to the LED driver circuit with respect to a measured output voltage and a measured current of the LED strings, respectively.